Catheters are flexible medical instruments for use in the introduction and withdrawal of fluids to and from body cavities, ducts and vessels. Catheters are used for many different applications within the human body including the administration of liquid therapeutic agents and the removal of bodily fluids for testing, monitoring, or disposal. Catheters have a particular application in hemodialysis procedures, in which blood is withdrawn from a blood vessel, directed to a hemodialysis unit for dialysis or purification, and subsequently returned to the blood vessel.
Typically, dialysis catheters define at least two lumens including a venous lumen and an arterial lumen. The arterial lumen withdraws blood from the patient and delivers the blood to a dialysis machine. The venous lumen receives blood from the dialysis machine and returns the blood to the patient. The venous and arterial lumens may include distal openings adjacent the tip of the catheter. In addition, the venous and arterial lumens may also include side openings which provide redundant or alternate flow paths to and from the arterial and venous lumens.
When a catheter is placed in a body cavity and fluid is withdrawn through a lumen of the catheter, e.g., the arterial lumen, the catheter opening or openings communicating the catheter lumen with the body cavity may become occluded. More specifically, because the catheter lumen for withdrawing fluid from a vessel draws a vacuum adjacent the openings, body tissue may be drawn into the distal and/or side openings of the arterial lumen and occlude the openings. Although the redundant flow paths created by providing both distal and side openings reduce the likelihood of total occlusion of the catheter withdrawal lumen, further improvements to known catheters to further reduce the likelihood of vessel occlusion are desirable.
Therefore, it would be desirable to overcome the disadvantages associated with known catheters by providing a catheter which is less susceptible to occlusion and capable of providing unobstructed fluid flow into the catheter.